As one of methods for producing amino acids by use of an enzyme, a method of asymmetric decomposition of chemically inexpensively synthesized 5-substituted hydantoin compounds as the starting material into optically active amino acids is known. This method of producing optically active amino acids from 5-substituted hydantoin compounds is important for production of pharmaceutical preparations, products in chemical industry, food additives etc.
In this method of producing amino acids from 5-substituted hydantoin compounds, the following enzymes (1) and (2) are necessary.
(1) An enzyme (hydantoinase) of catalyzing the reaction of forming N-carbamylamino acid by acting on a 5-substituted hydantoin compound to hydrolyze the compound.
(2) An enzyme (N-carbamylamino acid hydrolase) of catalyzing the reaction of forming an optically active amino acid by acting on the formed N-carbamylamino acid to hydrolyze the compound.
For producing optically active amino acids from 5-substituted hydantoin compounds, (1) hydantoinase and/or (2) N-carbamylamino acid hydrolase must be an optically selective enzyme, and a method of using a microbial enzyme system and a method of combining a microbial enzyme system with a chemical reaction system have been known.
For example, the known method of producing D-amino acids by a D-amino acid-producing microorganism or by enzyme-containing materials produced by the microorganism includes a method of using a microorganism of the genus Pseudomonas (Japanese Patent Application Publication No. 56-003034), a method of using a microorganism of the genus Agrobacterium (Japanese Patent Application Laid-Open No. 03-019696) etc. In these D-amino acid-producing microorganisms, their hydantoinase activity is generally often specific to D-5-substituted hydantoin, and when DL-5-substituted hydantoin is used as the starting material, only the D-hydantoin is hydrolyzed to form N-carbamyl-D-amino acid, which is further hydrolyzed to finally give D-amino acid only, as shown in the following reaction scheme (I).
D-Amino Acid-Producing Microorganism

As the method of producing L-amino acids by an L-amino acid-producing microorganism or by enzyme-containing materials produced by the microorganism, there are reports on a method of using a microorganism of the genus Flavobacterium (Japanese Patent Application Publication No. 54-008749), a method of using a microorganism of the genus Bacillus (Japanese Patent Application Laid-Open No. 63-024895), a method of using a microorganism of the genus Pseudomonas (Japanese Patent Application Laid-Open No. 1-071476) and a method of using a microorganism of the genus Arthrobacter (J. Biotechnol. 46, 63, 1996) etc. In these L-amino acid-producing microorganisms, their N-carbamylamino acid hydrolase activity is often specific to L-amino acids. Accordingly, when DL-5-substituted hydantoin is used as the starting material, both D- and L-hydantoin is hydrolyzed to give N-carbamyl-DL-amino acids, out of which the N-carbamyl-L-amino acid is selectively hydrolyzed by the N-carbamylamino acid hydrolase, to finally give the L-amino acid only, as shown in the following reaction scheme (II).
L-Amino Acid-Producing Microorganism

From a microorganism of the genus Flavobacterium out of the L-amino acid-producing microorganisms mentioned above, hydantoinase and N-carbamylamino acid hydrolase are partially purified, and the hydantoinase is known to be able to act on both D- and L-configurations of 5-substituted hydantoin compounds (Agric. Biol. Chem., 51, 737 (1987)).
However, because the above enzyme preparation is obtained by partial purification, whether the action of the enzyme preparation is attributable to the single enzyme or not is unclear, and the amino acid sequence of the hydantoinase derived from Flavobacterium and the nucleotide sequence of its encoding gene are not revealed.
From a microorganism of the genus Arthrobacter, on one hand, a hydantoinase gene and N-carbamylamino acid hydrolase gene have been isolated, and it is known that L-amino acids can be produced by a recombinant prepared using the genes. However, the hydantoinase derived from a microorganism of the genus Arthrobacter does not act on DL-5-(4-hydroxybenzyl) hydantoin, and can thus not be used for production of L-tyrosine from DL-5-(4-hydroxybenzyl) hydantoin.